Add [CachedAccessor] attribute to cache (almost) constant accessors (window.document).

third_party/WebKit/Source/bindings/templates/attributes.cpp

 {% from 'utilities.cpp' import declare_enum_validation_variable, v8_value_to_local_cpp_value %}
 
 {##############################################################################}
 {% macro attribute_getter(attribute, world_suffix) %}
 static void {{attribute.name}}AttributeGetter{{world_suffix}}(
 {%- if attribute.is_data_type_property %}
 const v8::PropertyCallbackInfo<v8::Value>& info
 {%- else %}
 const v8::FunctionCallbackInfo<v8::Value>& info
 {%- endif %})
@@ skipping 481 matching lines @@
                         ' | '.join(attribute.access_control_list) %}
 {% else %}
 {% set access_control = 'v8::DEFAULT' %}
 {% endif %}
 {% set property_attribute = 'static_cast<v8::PropertyAttribute>(%s)' %
                             ' | '.join(attribute.property_attributes) %}
 {% set only_exposed_to_private_script =
        'V8DOMConfiguration::OnlyExposedToPrivateScript'
        if attribute.only_exposed_to_private_script else
        'V8DOMConfiguration::ExposedToAllScripts' %}
+{% set surrogate_name =
+       '"%s"' % attribute.surrogate_name
+       if attribute.is_store_in_field else
+       '0' %}

[jochen (gone - plz use gerrit), 2016/09/15 08:20:51]

nullptr?

[Alfonso, 2016/09/16 14:21:48]

All the others callbacks seems to be using '0', I'm lost here.
Is this part of the updated guidelines, should I follow the new style or  mimic
the existing code?.

 {% set holder_check = 'V8DOMConfiguration::DoNotCheckHolder'
        if attribute.is_lenient_this else 'V8DOMConfiguration::CheckHolder' %}
 {% set attribute_configuration_list = [
        '"%s"' % attribute.name,
        getter_callback,
        setter_callback,
        getter_callback_for_main_world,
        setter_callback_for_main_world,
        getter_builder_callback,
+       surrogate_name,
        wrapper_type_info,
        access_control,
        property_attribute,
        only_exposed_to_private_script,
        property_location(attribute),
        holder_check,
    ] %}
 {{'{'}}{{attribute_configuration_list | join(', ')}}{{'}'}}
 {%- endmacro %}